An Army Corps of Engineers study finds a steady decline in commercial shipping on Chicago-area waterways in recent years. The study has stoked the contentious Asian carp argument and the debate over the future of Lake Michigan, the Chicago River, and the series of canals and rivers connecting the Great Lakes to the Mississippi River.

The Asian carp is an invasive species that threatens the health of Lake Michigan. The fish voraciously consumes nutrients that other species depend on for survival, and reproduces multiple times per year. Once Asian carp overrun an ecosystem, they are essentially impossible to displace. Groups working to protect the ecosystem support closing locks or installing barriers to prevent the fish from entering the lake, but the shipping industry claims that such measures will damage commerce.

A 2010 report by the Natural Resources Defense Council illustrates the tremendous challenges and opportunities the Asian carp crisis represents. As of 2009, Asian carp had moved past electric barriers along the Chicago Area Waterway System (CAWS) meant to keep them from entering Lake Michigan. In June 2010, a live Asian carp was captured in Lake Calumet – just six miles from Lake Michigan and beyond all barriers between protecting the Great Lakes. The standard response to such findings has been to apply toxic chemicals that kill Asian carp along with many other kinds of fish.

The Asian carp debate illustrates weaknesses in the region’s water infrastructure and raises the larger issue of hydrological or ecological separation – the technical term for severing the connection between Lake Michigan and the Mississippi River basin. Artificial barriers and chemical treatments are temporary fixes to multiple problems requiring permanent solutions. The Asian carp is just one of several invasive species that could move between the Mississippi River and the Great Lakes. The ecological and economic costs resulting from these invasions will mount until a permanent solution is implemented.

The reversal of the Chicago River was a monumental engineering feat that, along with the construction of the Chicago Ship and Sanitary Canal, linked the Great Lakes to North America’s largest river system and established Chicago as a national shipping hub. In addition to the ships moving people and goods, municipal and industrial waste traveled downstream rather than into Lake Michigan. Chicago was able to move its effluent to the Des Plaines, Illinois, and Mississippi Rivers, and the Gulf of Mexico instead of polluting the city’s water supply.

A 2009 study by the United States Geological Survey identified Illinois, the Chicago area in particular, as the single biggest contributor to the Gulf of Mexico Dead Zone. Nitrogen- and phosphorus-rich runoff from municipal and agricultural sources depletes oxygen and kills aquatic life in Gulf waters, thus creating a hypoxic or “dead” zone. In addition, the National Oceanic and Atmospheric Administration estimates that the Dead Zone costs U.S. seafood and tourism industries $82 million a year. Over the past five years, the average area of the Dead Zone has been 6,688 square miles, or roughly the size of the state of New Jersey.

Chicago’s antiquated water infrastructure does not separate stormwater from wastewater. Rainfall exceeding .67 inches can cause combined sewer overflows (CSOs), when untreated sewage and rainwater flood basements and enters local waterways. Storms producing over 1.5 inches of rain not only cause CSOs, but also can discharge sewage directly into Lake Michigan. Such events pose an obvious threat to public health and contribute to the flow of pollution wreaking havoc on downstream ecosystems.

The Army Corps of Engineers study shows that commercial traffic on the CAWS has declined steadily since peaking in 1994. Used primarily to transport coal, stone, iron and steel, and petroleum fuels, CAWS commodity traffic dropped from nearly 25 million tons in 1994 to about 16 millions tons in 2008, a four percent annual decrease and 36 percent overall drop. Opponents of lock closures claim doing so would harm the Great Lakes shipping industry, but advocates for separating the waterways, including officials from several Midwestern states, say the study supports their argument.

This trend is likely to continue. Trucking dominates freight transportation in the United States, particularly of distances under 500 miles, while most long-distance shipments move by rail. The vast majority of coal is transported by rail, and the scheduled closure of coal-fired power plants in the region should reduce local demand in the coming years.

Declining commercial traffic and invasive species create the opportunity to construct a regional network of waterways that meets the demands of the twenty-first century. Perhaps first among these is the protection of vital ecosystems upon which the regional economy depends, and an acknowledgement that simply transferring problems downstream is no longer acceptable.